Manual telephone system



' Feb. 12, 1929. 1,701,576

' J. H. LEVIS, JR

MANUAL TELEPHONE SYSTEM Filed Sept. 21, 1926 fil "Cu a INVENTOR w n 'U EAAMA BY v l? i I. l WWRPM T'*- ATTORNEY Patented Feb, 12, 1929.

Uht'iiTE 1,701,576 elite orFicE.

srrss JOHN H. LEVIS, 51%., OF ROCHESTER, NEW YGRK, ASSIGNQR T9 THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, (1F ROCHESTER, NEV YORK,

A CGRPOBATION NEW/V YORK.

IQANUAL TELEPEQNE SYSTETE.

Application filed September :21, 192

This invention relates to telephone systems and more particularly to manual telephone systems being specifically directed to his movements in so called feature cord circu for use in manual telephone systems.

. such systems wherein feature corrl circuits are useil, it has been customary to so arrange the circuits that certain features are suton'inticclly taken care 01', such. as associziti the operators telephone set with the cord circuit by means of a relay or relays, thus eliminating the usual listening hey. 'i as well. as other circuit arrangements such as advance plugging in -operatoi"s her, operetors listening; inrlicotion flesh recll, operutofls ringing control, calh ing subscriber ringing control, clerk key board, opere'tors cut in retard, etc, are features of this invention and will be (lescribed.

Another feature of this invention consists in arranging the circuits in such a way that reverting cells or cells for wanted subscribers on the same lines ceiling subscribers are handled in the following manner: The opcrater answers an incoming call and finds that a party on the same line is clesireth after which she instructs the calling party to hang up the receiver and again remove it when the bell rings. The operator then substitutes the co ing cord forthe answering cord. and tie presses the proper ringing,- button C-OI'LGSPGEIClto the caller; i ertys station and utter is ion she operates the r11 Welling to the outlin ff station. A! v i operation she tie} i non-ring hich cli. connects the conr' g relays from the circuit. ibers IGiDQVQ tneir rec rv is furnished over the line 2: until disconnection.

i the nccoinpnnyin drawing, it is t1 the invention will best be untlcscribing the method of estab- FI, n ephone connection from a cell- 'tstion such will to a wanted substa- Vi hen the subscriber at A itizites a cell by removing his receiver from t e switch-heels a circuit is completed "from ground, inner bnclr contact of cut-cit relay 1, over the line and substation circuits in se- =ics, outer back contact oi cutcfi' relay 1 and cord which remains in Serial No. 13 3,53).

relay 1 to ground. The operation of relay 4 c is effective to short-circuit its high resistance winding, e-tter which suiiicient current flows in the sleeve circuit for operating cut-oft relay 1. The operation of relay 1 cliscon nects ground and grounded battery from the line conductors of the calling line and opens the circuit ct and releases relay 2, which cxtinguishes the line lamp,

It will be understood that in case another operator heel inserted the plug of an answering cord into the jack oi this ceiling line before plug P was inserted in the incl: oi this line as above ilescribeih relay ief the cord circuit uscil by the first mentioned onerctor would have been energized and the circuit to g ounded battery on the sleeve of the arch J would have been connected through the low resistance winding of relay 4 Then when the secoinl operator endeavored to an :m'er this ini'necell when pin P was insertertinto nch if, the low resi nee (jlt'i'tllit to battery would he eilcetive to 'cnt the one; '1 o, relay tot the second opcrzitofis -'l1us pring the simultanerelay 7, mg of nioy 5, back Contact of relay end lower niche con-tact incite contact and winding' of relay 5,' over the previously described circuit, to ground at the lower make contact of relay 4. This last described circuit operates relays 7 and 10, relay 7 disconnecting the circuit previously described extending to grounded battery, through the common resistance coil (3, thus removing battery from the operating circuit or" all other relays similar to of other cord circuits at this particular position, the purpose of which is to prevent any other cord circuit being connected to the operators circuit during the time this particular cord circuit is connected as above described. Since the operating circuits of all other relays 5 extend by way 0t conductors similar to 8 to battery L irough the normally closed contact of relay '7, it will be seen that when relay is energized, thus opening the circuit to battery, through coil 6, no other relay similar to can be operator The insertion of plug P into jacl: J in addition. to closing circuit for operating relay extends the calling; line circuit to ground and grounded battery through the windings of supervisory relay 12 and this relay is operated over the two sides of the line. A circuit is now closed from grounded battery, answering supervisory lamp 125, upper make contact of relay 12, outer left hand back contact of flash recall relay 1%, contact 15 of relay 5 and right hand winding of common relay 16 to ground. Sufficient current flows over this circuit to cause lanzp 13 to be dimly lighted as an indication to the operator, that her telephone set is connected to this particular cord circuit. This feature is l 110\ "i as the operators listening indication, since the dim answering supervisory lamp indicates the cord to which the opera tors telephone set is connected.

il ith relay 16 energized circuit is closed for operating position register 17, which reg;- ister is for the purpose of recording the number of connections established at this iarticular position. Eelay 16 is now locked in its operated position, from ground, make contact of relay 10, inner left hand make contact and left hand winding of relay it; to grounded battery. Relay 16 establishes a circuit for holding relay 7 in its energized position through the left hand winding of relay T.

Relay 5 extends the tip T and R conductors leading to the common open. ors set to the upper and lower sides of the talking circuit, respectively, and the operator new requests the desired number. At the upper make contact of relay 5, the tip of tie calling cord is connected to the common busy test circuit ET, so that this circuit is etl ective to indicate to the operator in the well known manner when the tip of plug P is connected to the sleeve of jack J whether or not the called line is busy. It it is busy the operator will hear a click in her receiver and will so inform the calling subscriber, but if the f is idle the operator will insert the plug into the jack J associated with the called station E.

In addition to the above mentioned circuits which have been above discussed, the operation of relay 5 closes a break-point in the common rcvertive busy tone circu t RBT to the sleeve of the answering plug P. This tone corresponding to the tone source ll of White Patent #1552568 is therefore temporarily associated (through contacts of a relay similar to 16 oi said patent and functioning; in the same manner) with the jack of the calling lii e during portion oi the time that the operators telephone is connected to this cord circuit, and in the event that the called party located on the same line with the call ing party, when the busy te. made as above pointed out, r] L cial tone will be e ended from the jack of the :alling line to which the tip of plug P will be in con nection and thence by way oi the upper back contact of sleeve relay 1%), right hand back Contact of relay 9 and upper make contacrelay 5 to the common busy test circuit. lVh-en the operator hears this particular revertive b .sy tone she will understand that the called party is located on the same line with the calling party, in whicn event she vill inform the calling subscriber to hang up the receiver and wait until the bell at his substation ring". This is known as a reverting call and the operation will be described later.

Assuming that the called line is idle when the test of the jacl: associated with substation B is made, the operat' will insert the plug; l? into jack J and operate some one of the common ringing selecting: buttons, shown in the upper portion of the drawing;

A circuit is now closed from ground, windinc; ot cut-oil" relay 36 associated with th called line, sleeve contacts of the jack J an, plus: i and windine; of re e 20 to ermineed battery. Relay as is operated in this ci cuit to remove the battery bridge i called line and relay 20 operated ch circuit from ground, make contact oi rent 20, continuity spring and burl: contact 0 relay 9 and left hand winding of relay 2 to grounded battery. Relay .21 is opera cu in thiscircuit and functions to connect the common frequency selecting keys and relays to the particular cord circuit. which is in use in connection with this call.

Assuming that M cycle ri ine acne-rotor is required for operating the ell ot' the wanted substation, the operat ringi key 2, which is e? circuit for momentarily op The operation of relay 23 closes a, circuit for ighting the 33 cycle ringin lamp, which serves as an indication to th operator that this PZU'tiCHlRI frequency is connected to the cord circuit. The operation of relay n3 also extends a circuit from ground through its KilltfLCt of relay 31 and make conv 20 to ground. The operator n plugs from their associated no the circuit 1n condition tor a succec 1: c

In the event that the calling st bscriber at substation A desires to initiate a recall be fore the connection has been ta zen down, he does so by temporarily opening the hookswitch contacts by moving the hook-switch down and up. This is elibctive to oven 1: inentari y the llfll iilng circuit of role. which retracts its armatures and t l closes acircuit "For the lash 1 cxicnding from grounded battery, 1 relay 1-l, lower l ack contact of relay 1; hack contact of relay 31 and make con relay 20 to ground, relay 20 being cne due to the fact that plug P is will in ass tion with jack J. llelay l-ion opera. closes a locking circuit for its-elf through its inner left hand make Contact, lower had contact of relay 31 and make cor 20 to ground. This last described locrtirg circuit is independent of the control of ti relay 12 and when the calling subscribers l' circuit is closed, relay 12 is actuated, whicl effective to establish a circuit from groun battery, lamp 13, upper make con 12, outer left hand make conta o 1 flashing interrupter relay 4:1 ant counnon flashing interrupter 4-2 to ground. T his ci cuit causes lamp 13 to flash and by the operation of relay a l also flashes connnon lamp 423 to call the attention of the operator to lann 13, which is an indication for her to remove the plug P from he jack J and ascertain the number that the calling subscriber now dosires. This is known as the flashing recall feature.

Since this drawing represents an A operators cord circuit and associated apparatus, the operation of the system will now be eX- plaincd in connection with trunk calls or ails to a distant oliice. it is propomd to operate such trunllt walls by 1; of the so-called i 1 1 i led wsa,

straight i'orr-xard trunking scheme. the; is the A opera or siznplr plices pin i into the jack associated. with a trunk lc... .n to a 'llS- 2'3 taut ofiice and operates the non-ring key an appearing in the upper left hand portion of the d awing'. In this system it is not neces sary to make use of? order wires for ordering up trunk connections.

l i hen plug P is connected to a trunr ack T as shoi n in the lower right hand portion of the drawing. a circuit is closed from ground, resistance 44, which corresponds to a cut-off relay, sleeve contacts of the jack and plug P and winding of relay 20 to grounded battery. The tip ring conductors of the calling end of the cord circuitare now in connection with the tip and ring trunk conductors and since the signalling on this class of a call is done by means of the battery -lied Over n13 ant the trunk through windings of relay 31, it is not necessary to ring over the trunk. In fact it is ecessary to disable the ringing apparatus on a connection of this kind.

The operation of no i-ring key NB. closes a circuit for operating relay 45 associated with this key and this relay '1. turn closes a circuitfor lighting the no airs; lamp NR as an indica ion that this re is in its operated position. A circuitis also closed from ground,- right hand make contact of relay d5, outer left. hand make contact of relay 21 and winding of relay 26 to grounded battery. Since none of the frequency ."electiug keys are operated on this class oi call, the circuit through :ct 2 1-, and right hand winding of cont: relay 21 not ellwtive with the result that we operated. Relay 9 is op extending from grounded l winding oi relay 9. conand right hand make conground. Relay 9 is then .i position through its right hanc ,r'lll lin to ground at the contac' of relay 20. it will thus be seen that the talk nection.

When rel y 9 operates. tne circuit of relay n ma (e contacts of this relay. Relay 26, however, is locked in operated position in a circuit extending from grounded battery, winding of relay 26, inner righthand make contact of relay 26, inner back contact of relay 1%, lower back contact of relay 31 and nake contact of relay 20 to ground. At the left hand back contact of relay 26, the circuit of the calling supervisory lamp 29 is opened and when the caller subscriber in the distant oliice responds, low resistance circuit is connected across the trunk conductors in the well known manner. which is e ective to opcral" rel y 3;, which (rpens the above traced lockii. V circuit for role 26 allowing this relay to deenei '..e and es ablish a break point in the Cll'Clllb oi the calling supervisory la1np29,but this lamp is not h. 'htcdat thistiinc because relay 31 is energized. l Jhen the calling subscriber at the distant on d rep aces the receiver on its switch-hook, relay 31 deenergizes and closes the circuit for li lamp 29. ltwill thus be seen that 3y means of the left hand back cont .ct o-l relay 26, the dark keyboard feature is retained on trunk connections.

The operation of the circuit will now be cscribed in connection with reverting call, 1 a all from asubscriber such as sub- 1.1., assumed to have a 33 cycle. bell,

q subscriber on this same line, assunedto have a 16 cycle bell. Line lamp 3 is operated in the manner above describec and the call is answered in the same manner as in the preceding case and with relay 5 operated for connecting the operators set ill) to the cord circuit the common revertive busy tone circuit ill-Bil is connected by way of contact 4;? of relay 5 to the sleeve term' 11s of plug P and jack J in the manner previously outlined. W hen the operator touches the tip of plug l? to this jack for testing the called line, the revertive busy tone is applied to her telephone set as anindication that the called party is located on the same inc with the calling party. 'lhe operator now instructs the calling party to hang up the receiver and wait until his bell rings. She then suh stitutes plug P for piug P, which is effective to operate relay 20. l

A circuit is now closed for lighting calling supervisory lamp 29 extending from grounded battery, lamp 29, left hand back contact of relay 26, contact of relay 19, inner back contact of relay 31 and make contact of relay 20 to ground. A circuit is also now closed tor operating relay 1l extending from grounded battery, winding otrelay 1%, lower back contact of relay 12, lower back contact oi relay 31 and make contact of relay 20 to groin l. Relay it is locked in its operated position by way of its inner make contact, lower back contact of relay 31 and make con tact of relay 20 to ground. A circuit is also closed for operating relay 21 extending from grounded battery, left hand winding of lay 21, back contact and continuity spring relay 9 and make Contact of relay 20 ground. 7

At this time relay 9 is not operated, since operating circuit is open at the middle I contact of relay l i. The operator now depresses rir ing key which is eli 'ective to apply 16 cycle of to ringing current to the line, since it has been assumed that the called station issignalled by this frequency. The operation or this key closes a circuit for operating relay 5t and this relay in turncloses a circuit for operatingrelay 19 eiitending from ounded battery, resistance coil 25, winding of relay 19, right hand winding of relay 21, conta t of relay 21, leftliand make contact cl relay to ground. Relay 19 is not locked at this since its locking circuit is open contact 5'? of relay 14:.

c 'cuit is now ellective for operating cc relay criendi" f om w of 32, contact 33 of l t hand winding of relay 9 y. Relay 32 is of: sufiicientcc, for example 5000 ohms, operation oitrelay 9 in the ib-ed. circuit and when relay acts its arn ure, a circuit is closed for v This latter relay estah- .14 for operating relay eX- 'lroin oui'ided battery, winding of contact 61 or relay 59, and key conl ound.

ted. 16 cycle enerator current is led t0 the cal ed line extending from this generator, left hand make contact of relay 60, left hand back contact of relays 63,641- and 65, outer right hand make contact of re lay 21, winding of relay 38, inner, lower make contact of relay 19, ring conductors of the mug l and jack J over the line and substation circuits in series tio conductors of 1 i, a l p r: a plug l and upper make contact ot relay 19 to ground. Upon tl1erelease of key 55, relays 56 and 60 are deenergized, thus resulting inthe application of ringing current to signal the called sta tion only during the time that the ringing key is depressed. ln'other words on a connection of his class the ringing is manual instead of automatic.

The circuits to the interrupted generator leads appearing in the lower portion of this drawing not effective at this time, since ringing currentis only applied to the called line, while the keyis held in its operated position and at this time relay 21 isenergized which maintains conductor 70, overwhich interrupted generator is applied to the cord circuit, in its open condition.

The operator now depresses key 22, since it is assumed that the calling station is signalled by 33 cycle generator current. The operation of this key operates relay 23 and this relay in turn again operates relay 19 over the circuit above described, except that this time the current is applied at the left hand contact of relay 23, instead of relay'56. Relays 32 and 59 remain energized and a circuit is now closed -from ground, contact of key 22, inner make contact of relay 58 and winding of relay 65, to grounded battery. Relay operates and connects uninterrupted 33 cycle generator by way or" its left hand make contact over the circuit previously deibed for ringing over the called line. This s1 nals the calling station; It will be noted t i it relay 9 is maintained in its normalposition and in order to operate this relay and CtUSGtllG;Cll'CUltto function as required it is necessary for the oper tor to depress non ring key NR, wl ich is ellectiye to close a I circuit for operating relay 4:5 and this relay in turn operates relay 9 over a circuit extending from grounded battery, right hand winding of relay 9, contact 33 of relay 21 and right hand make contact of relay L5 to ground. l'lela 9 is locked in its energized position to the ground at make contact of relay 20 and at the back contact and continuity spring of." relay 9, thecircuit of relay 21 is opened and thisl'atter relay deenergizes, The circuit now in condition waiting for the response of the called calling subscribers.

When either the calling orwanted station removes the 'receiv'ertrom its switch-hook, a;

circui is closed for operatinrr relay 31, which opens at its inner back contachthe calling common to it supervisory lamp circuit, which is effective to extinguish this lamp. Relay 31 opens at its lower bacl; contact the circuit which looks relay ll in its energized position and this relay now deenergizes. In this type of connection talking batte y is fed to the line for both calling and called parties through the winch lZS of relay 81 and when both 01": these subscribers have replaced their receivers on their switchl1ool:s, this relay deenergizes and closes the circuit for ighting supervisory lamp 29 as above described and the lighting of this lamp is an indication to the operator to remove plug P from jack J. after wiich the circuit is restored to normal condition.

It sometimes happens on a revertive call that the operator fails to operate non-ring hey in which case the circuit would not be in proper condition and would not function properly. In this case relay 9 would not have been operated and when one oi the subscribers removes the receiver'lrom its switch-hook, a circuit is closed from grounded battery, lower winding of relay 31, inner ath contact of relay 19, ring contacts 0t plug P and jack J over the line and substation circuits in series, tip contacts of the jack 5 and plug P, upper back cont-act of relay 19, outer right hand back contact relay 9, upper back contact of relay 5, back contact of common test key and wind ing oi relay 75 to ground. This is effective to operate relay and connect the common flashing interrupter ."y way of a make contact of r lay 75 and a back contact of relay in through lamp NR to grounded battery. This lamp is flashed over the above described circuit and since it associated with non-ring key NR, it is an indication to the operator to depress this key, after which the circuit will function properly as above described.

it sometimes happens that it is desirable a multiple jack when the operators one set not connected to the cord cirn' which rola i a would be in its ition in such an instance it is ary for the operator to depress the hey shown just below relay 75, wnich is ltective to extend the tip of the plug i to the common test circuit.

Referring back to the time when ringing curr it was applied to the called line, it will now be explained how the feature calling subscriber ging control is provu'led. This teat ecu. in the provision of means when j the ringing current is disconnected from the called line it the calling subscriber hang up the receiver during the ringing interval.

it will be remembered that relay 19 is locked energized at the time ringing current is applied to the called line and in the event that the calling subscriber disconnects this time. the locking circuit of relay 19 is opened at the armature and contact 5"! of relay i l, since thislast named relay has its energizing circuit closed at the lower back contact and armature or the answering supervisory relay when the calling subscriber opens his line circuit by hanging up his receiver. This results in the disconnection oi the ringing current from the called line by the deenergization of relay 19.

.lt will be seen from the above description that a. cord circuit and associated apparatus hare been provided, by which it is possible to render extremely eiiicient and rapid service in a manual telephone system with a minimum number of operations required by the operator.

1 claim:

1. In a telephone system, a plurality oi telephone lines, each of certain of said telephone lires being provided with a plurality of substations, neans including a plurality i cord circuits ior telephonically interconaid substations by two different interrupted ringing cursubstations, sources of unincurrent of different chart i stics, a. sh e key for each source of said interrupter iging current-,szud keys be r lug common to said cord circuits means includ" said keys tor selecting and associat- 11 a source oi interrupted ringing current nu i a cord circuit taken for use in one method of interconnection, and means including said keys for associating a source oi? uninterruptee ringing current instead of said interrupted ringing current with a cord circuit taken for use in the other method of interconnection. v

In a. telephone system, a plurality of telephone lines, each of certain of said telephone lines being provided with a plurality s bstations means including a plurality of circuits for interconnecting said subs, sources or into 'rupted ringcteristics for ationsr sources oit ditl'erent eha said sub o 'inging current of (llllQlGZli. charau'cristics a single key for each source of interrupted rinoing current, said keys beinn common to s cord circuits means including ol l lie g s 't'or associating a source or intcrruf ited ringing cu rent with a. cord cir i alien for use to gnal the cinled subsiz tion only and means a 'luding said keys for 7 sources oi" unintu'ruptcd ringing with a cord circuit taken tor use to nd calls-6 substations oi a connection. i

3. In a telephone system, a plu 'ality of telephone lines, each of certain ofsaid telephone lines being provided wi l a plurality of subns means including plurality oi cord circuits for telephonically interconnecting said sul stations by two dillerent methods, an ooerators telephone setcoininon't said cord circuits. means responsive to the connection of Ill) LII

A 9, l ope/Mimi ieist connecting ie set to said cord cii'ci, t, sources of interii'upted inging on rent of dili'ei'ent chmrzictoi'istics for selectively signalling said substz ions, sources of uninterrupted i'i. gins) current- 0-5517 "'ei'ent characteristics, a single fol ech source 0' interrupted i' f, said keys bein connnon to said coi'd circuits, means includin said (eys for asso :iztting said interrupts ringing current with it cord i 11 1'01 use in one method oi int meens ineludii a; void keys to imintei'ruptee i v a cii'cuie taken for use inteiconneetien. i

i. In :1 telephone system, a plu 'ality of: tilione lines, certain of which are party zemts includi e plurality of interconnecting seidtelephono lines, "milzissmiietedwi h e2, 2h cord oil inten ing); current .Wi'sci'ei'isti 4 selectively sigpziity lines, 5011- f uninen 11;;- Current 01 oil :iiziclici a i 1 i'upted inon to said cord ssidkeys for associating sine interrupted ringing nii'ent with a cord circuit then for use one ail of one clnss,n1oen 1,; mid keys for associating said unint c ing' current with a cord circuit tslien 101' u on a tail of another class, and means iesponsize to the initietionof a recall on a cell of said first class for dist-incti'vel oaeisting' ssid supervisory. signal. i

5. In a telephone system, a pnn'eiity of telephone lines, certain 01" which are party lines, means lndi g e cord circuit for iiiiei'conn-ieting' 2 pet of said tele ghonc lines, means inc n said cord CilCd i est: 1

l with a cord other method oi word cinusup' cm of dili'erent c nailing c i ru ted ring bet-CS,

lashing e we live connection i'9l"t'11pi0(l 1 se millingl in uninte. ed 1 ei en? a felled vine on said i'ei eii e,

interrupted cy being eoininoa s. means includi i'i ngrging liii'nlity keyfor cmcent mtei'ru; 1, l

sources of interrupted ringing Cdl"ei1'u ferentcharacter]. ties for seieci'inp; and inatically signaling stations on said lines, sources of uninterrupte ringing CT'IETOHt o difiei'entcharacteristics for selecting an. manually signalling stations on said lines, a

"le hey common to said cord circuits, means A e one of said psn lines, societ es said uninterrupt- With one of said coi'd ciri' U n telephone system, :1 plurality of teleilione ,nnes, certain of Whie 1 are party lines, ,1 s including a piui'siity of cord circuits for nterconnecting said telephone lines, a supei'visc iy signal associated with each cord W mess of interrupted ringing current 'ent cln'iv *ecteristics for selectively sigseid party lines, sources oi unintei' 8. in teleoli deity lines, a pier a plurality of cord circuits at each of said positions for interconnecting said lines and for establishing revertive connections, an opei'e tors tel phone set common to said cord cob ne s silt of operators positions,

ringing current of different ohmic- "ingle key for each source of inten $5 r nging current, ssidiieys being coincord circuit-s in 15 incliujl ll said socintine; said in irupted nnging cuinen jth :1 cord circuit taken for use on a cell oi. one ole" ,"iiidii s including l' ys for. iii?- essoeiziting said uninterrupted ringing on;- rent with ecoii-d cii'cuit taken for use on :i cell of "Aether ciess, and nieens responsive to the initiation or a recall for distinctively op crating seic supelvisory signal. 95

i i stem, a plurality of cuits at each position, means responsive to the connection of s cord circuit at pluralit of said posi ions to one of said line h ssociets telephei cc L lesion of other opeistor teleel sets, sour es Y interrupted ringing on 11. different el- -icteiistics for seleeti eij M Li *ty lines, sources of uninteniupted 12' current of diiiieiei chei'ectel l ist-ics, :i ng \3 key for each source ofinienrupted current, seid keys being coinmon to said cord circuits, means including: said keys for sssoeiating said interrupted i cm'rent wit? it coi'dcii'enit taken for All? 111; n pair of telephone hiding; ueid lnaystoi 21sei'iupted ringing current 'cuit taken tor use in n. revei'tive WI oi? cone circuits at said position intone-oi ect-in SEtltCi lines and for e l ectlons, seep-ens )1 e ition t of o i'hcr connection bccurrent of o n i'he same iII1Q,SOiH'-JGS oi? i11- iiiciy sig: current for signzriiing Oil e 1011, sources of iriiniierriiipted u 3 cm .i for sigz'imlling on said reverrup'tcd rin i cc iiiiectioii, means inciiuiing a si* gic key mon to said c-omiiion to e phiirziiit cord circuits r01 as said keys for C rmg ngcurrt Wiiil a cor use in interconnecting sociziiiing 1. source of said inicrruptcd ringing currcnt with "no. cord circuit, means for dis- .:oiincct g scurcc of iniorrupted ringing lines, and no in currcnt a i said corci circuit upon the resocizrting sari rri Mailed 1011, means including wlth a cord circuittsizei a single hey imassociating a source of said.

connection.

10. In a oley/hone system, a telephone line, lines, xiiesns circuits for ii lines, asupc each cord circuiz, commoii to u sire to the co iii'linterrupteo r' circuit, and 111211: rslity of co A irciits for disconnecting said. source of un nterrupted ringing currentfrom said cord circuit.

In a iciephoiic plurality or -ho11c lines Ctiilili of wiiich arc u, means including a cord circuit ior csconncmoi'i beiwccn 21 cal int" mg current with said corc mm of incii are a, L calling ieiepho 9 4c siaiiion on encii \ih'i :1 calls station 0; 1m ers ors telephone sc other line, incsns iiicluding scord circuit for eispiaying said for cstsbiishi'ig s rovortive conncciion besources of interrupts in'vecn stations on Lo $211116 line, sources of interrw atcci ringing- "of for Sig oiling on ling; said party}. si 11, sorrccs of unin crru vies- 1 5 first connecti:

{ ringing curreni'oi? diiTerciit ciiaiuc'icrisi'cs, l a single key for each source of intcrrupiiird c coixiicc .or ircsns ri ging current, said keys boin common to ion iii? a piur 't ssic. cord cir nits means i in said izc qs for assoc s g so: int rruptei ier-ib taken 1 L with a cord ci cri of one 01$. 5

.r r of said coiled stsi :1 ing W singio key for s o. .icrcn izrerrnpiicti 1; b I said signal in :1 (iii? 5911f circuii, zinc a non-r o common to 1 of cord circuits disconnecting aterrupied ringing; current circuit.

disconnect signs}.

11. In a teicnhone and a coiled lino" ii of cord circuiis y such cori ir me are P i'ion 2 51i said cord circ connccti n sources of killing: on

common to semi c sziiii 1-10 for r125 ringing ciiri'en (ii'CUJrH only wocn .Zii2 z! and me: us i said uni: cord circir said, cord. line.

too 1'1 u first comic: no current circui's for ifccrrupi'ed ringcircuit, means for ten-opted. ring;-

to a plurality i'ng' said source of uninterrupted ringing current from said cord circuit, and means for indicating to the operator that said non-ring key must be operated.

15. In a telephone system, a. plurality of telephone lines, certain of which are party lines, means including a cord circuit for establishing a connection between a calling station on one line and a called station on another line, means including said cord circuit for establishing a revertive connection between stations on the same line, sources of interrupted ringing current for signalling on said first connection, sources of uninterrupted ringing current for signalling on said revertive connection, means including a single key common to a plurality of cord circuits for associating a source of said interrupted ringing current with said cord circuit, means for disconnecting said source of interrupted ringing current from said cord circuit upon the response of said called station, means including a single key for associating a source of said uninterrupted ringing current with said cord circuit, a non-ring key common to a plurality of cord circuits for disconnecting said source of uninterrupted ringing current from said cord circuit, and means common to a plurality of said cord circuits for indicating to the operator that said non-ring key must be operated.

16. In a telephone system, a plurality of telephone lines, certain of which are party lines, means including a plurality of cord circuits for interconnecting said telephone lines, each cord circuit being provided with an answering plug and a calling plug, sources of interruptedsignaling current of different characteristics, a single key common to said cord circuits for each source of interrupted signaling current, each of said keys being individual to one of said sources of uninterrupted signaling current, means including one of said keys for associating one of said sources of interrupted ringing current with a cord circuit taken for use in interconnecting one telephone line with a second telephone line, and means controlled by the connection of the calling plug of a selected. link circuit to the calling telephone line for placing said sources of uninterrupted signaling current under the control of said ringing keys to signal said last mentioned telephone line.

17. In a telephone system having telephone lines each provided with substations responsive to signaling current of different frequencies, link circuits for interconnecting said telephone lines, sources of ringing current of diflerent frequencies to signal the substations on said party lines, and a single ringing key common to said link circuits for each source of ringing current, the method of signaling said telephone lines which consists in using said keys to select interrupted sig naling current of the proper frequency to sig-- terlstics for selectively signaling said party lines, sources of uninterrupted ringing current of different characteristics, a single key for each source of interrupted ringing current, said keys being common to said cord circuits, and means controlled by the condition of said answering supervisory relay for placing said interrupted or said uninterrupted sources of ringing current under the control of said keys.

19. In a telephone system, a plurality of telephone lines, certain of which are party lines, means including a plurality of cord circuits for interconnecting said telephone lines, an answering supervisory relay and a calling supervisory relay associated with each cord circuit, sources of interrupted ringing current of different characteristic for selectively signaling said party lines, sources of uninterrupted ringing current of different characteristics, a single key for each source of interrupted ringing current, said keys being common to said cord circuits, a relay associated with each cord circuit for deter-- mining'whether said interrupted sources of ringing current or said uninterrupted source of ringing current shall be employed in signaling a telephone line, and a circuit for said relay controlled at back contacts of said answering and calling supervisory relays.

In witness whereof, I hereunto subscribe my name this 18 day of September A. D. 1926.

JOHN H. Lnvrsn. 

